Wednesday, April 09, 2014

Comfort Blanket?

As AHVLA carve up the country into areas of 'Risk' from zoonotic Tuberculosis, the comfort blanket of four year testing outside the High risk and Edge areas has once again, taken a hit.
A dispersal sale of a cattle herd from Cumbria, sold in Cheshire, has subsequently revealed several reactors. Farmers Guardian -[link] has the story.

This is not the first time that this has happened, with this sale in 2010 - [link] causing similar problems. Unfortunately farmers purchasing stock are often quite unaware that in these 4 year testing areas, no test is required before any dispersal sales and several do ask for stock to be tested prior to purchasing.

One of our veterinary sources has sent this comment:
It is also worth noting that cases of herd breakdowns are not that uncommon in Cumbria - years ago the outbreak can clearly be seen in the Dunnett Report maps.

The cluster of cattle cases was, at that time, as big as a cluster in the Midlands. Interestingly, the source was traced back to a couple of infected badgers.

Subsequently, it was found that the Cumbria area had its own TB type. The spoligotype was the same as one of the Midlands outbreaks, but the VNTR typing was different.

This type was found in badgers and cattle from the area and I believe that all the outbreaks from elsewhere with this type (that could be traced), traced back to Cumbria.

So, rather inconveniently, this is a TB endemic area. This has been known for decades.

So why is Cumbria on 4 yearly testing?

Why indeed.
Test and ye shall find.  More testing inevitably reveals more 'problems' in sentinel cattle. 

The Manchester Ship Canal and a large urban area look good on a map and are also thought to act as a badger barrier.  But that conveniently ignores the infected Cumbrian bred residents already behind it, and the untested alpacas and translocated badgers happily leaping over it.

Further speculation as the source of this outbreak is futile until AHVLA's team have done their spoligotyping of the type and VNTR responsible for this outbreak, in what, on their maps at least, should have been a clean area.
Meanwhile Defra's comfort blanket has a few more holes.

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